Automatic telephone-exchange system



.8. G. DUNHAWI.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM,

APPucATmN FILED JUNE 7, 1915.

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BERT G.-DUNHA1VI, OF HAWTHORNE, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN-MENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEWYQRK.

i AUTOMATJQC TELEPHONE-EXCHANGE SYSTEM.

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Application filed June 7, 1915.l Serial No. 32,688'.

To all whom t may concern:

Be it known that l, BERT G. D UrIHAM, a citizen of the UnitedStates,'res1d1ng at Hawthorne, in the county of Passaic andy This ises1' ecially'true in full automatic sysv tems, that is, in systemswherein the selectors and connector are set by a sender nianipulated bythe calling subscriber, since some of the impulses would be lost -iftransmitfwl before the finder had reached thecalling line terminal.

It is the object of this invention to provide a circuit arrangement forautomatic finder switch s of the two-movement type, wherein this int`l'val 'is reduced to a minimum.

A feature of the invention istheprovisio'n of an efficient findercircuit arrangement of this type which obviates the necessity of a sideswitch or similar electro-mechanical control switch.I y

Referring to the drawing which illustrates only so much of a telephoneexchange system as is necessary for a comprehension of the invention,the lines terminate as f calling lines. in multiple contacts 41, 42 of anumber of automaticrlinder switches, a multiple test terminal 40 beingalsoassociated with each line. The lines are d1- vvided in groups, thefinder being adapted not shown), during the primary movement of suchshaft in search of the calling line group.; Each groupy switch 5 1s alsoprovided with a home contact 29, upon which the brush 25 normally rests.Each group of lines l1s also provided with a relay 17 which may beenergized by any line relay 10 of the same group. T his relay, whenenergized, removes ground `from its multiple contacts 6 in the findergroup switches, and simultaneously grounds starter wire 22 leading tothe primary stepping 'magnet 1S of the pre-selected finder. The primarymagnet 18 steps the brush shaft in a primary direction until the brushencounters the multiple group contact (3 of the calling line group,froml which ground was removed by the energization -of the correspondinggroup relay 17. The primary movement of the brush shaft is then stopped,at which moment the linder brushes 31, 32, 33 are in operative relationto multiples of the calling line group in the finder. The secondarymovement of the brush shaft is then initiated, the test brush 33'in`this movement wiping over the test terminals a0 of the lines in thecallingl group. When such test brush reaches the calling line testterminal 40 therein, it operates the cutofi relay 12'thereof which isconnected to sald test terminal. The cut-off relay thereupon opens thecircuit of the line relay 10 which in turn, by opening the circuit ofthe' group relay 17 and removing ground from starter wire 22, causes thefinder brushes to stop in connection with the calling line.

A general outline of the system hav-ing been given, the ,operationsinvolved in extending a calling line will now be traced in detail.

The removal of the receiver by the subscriber at substation A energizesthe line relay 10 over the following circuit: free pole of battery, leftwinding of line relay 10, conductor 11, left armature and backl contactof cutoff relay 12, line conductor 14, the telephone set at substationA, line conductor 15, inner armature and back contactof cutoi'l relay12, conductor 1G, right windingl of line relay 10, to ground. Theenergization of the line relay 10 closes the circuit of relay 17, commonto this group of subscribers. This relay, upon its energization, closesthe following circuit for the primary stepping magnet 18 to move thefinder in a primary direction in search of the group of lines initiating.the call; free pole of the battery, pri-- mary magnet 18, its armatureand back con* tact, conductors 19 and 20, primary off-nor# mal springPON', starting conductor 22, armature and front contact of group relay17 to ground. Relay 1s energized in multiple with the primary steppingmagnet 18 by way of conductors 24, 20,V primary offnormal spring PON toground, over the circuit just traced'. itself to ground over thefollowing circuit:

.free pole of battery, `relay 23, its inner armature and front contact,conductor 28, Contact brush 25, home contact 29, conductors 30, 19,

I 20, primary off-normal spring PON, starting conductor 22, to ground atthe armature and front contact of group relay 17. Thus, the primarymagnet 18 steps the brush shaft in a primary direction as long as itscircuit is closed at the inner armature and f-ront contact of relay 23,which circuit is in turn f maintained closed as long as the brush of thegroup switch S encounters contacts 6, grounded at the armatures andbaclrcontacts of-the relays 17 of non-calling groups.

7h/en the contact 6 of the calling line group i is reached, which Yisassumed to be the first, and from which ground was removed by theenergization of the group relay 17, the circuit of relay 23 is openedand the de'energi- -Zation of this relay opens the circuit-of theprimary stepping magnet 13,- thus causing the primary movement of thebrush shaft to be stopped with the brushes 31, 32 and 33 in operativerelation to the group ofalines4 ,containing the calling line whosesubtuton ductor 22, to ground at the armature and front contact of saidgroup relay, and after the first primary step of the finder brush shaftand the consequent transfer of offnormalv spring PON to its lowercontact, this relay locks itself over the following circuit: free poleof battery, relay 38, its upper armature and front contact 37, 'start-Iing conductor 22 including spring PON',

armature and front contact of group relay 1 7 to ground'. Thus thedenergization of relay 23, as brush 25 reaches 'the ungrounded callinggroup contact 6, and consequent engagement of its outer armature andback contact, immedlately closes the following ...circuit for thesecondary stepping magnet 34 to movethe finder brushes 31, 32, 33 overthe `4yterminals of the selected group in search of the `calling linetherein: free'pole of the battery, stepping magnet 34, its armature andback contact, conductor 35, outer armature and back contact of relay 23,conductor 36,`

upper armature and front Contact 37 of relayl 38, starter Wire 22including spring This relay 23 then locks -relay 17'to ground; .L

low

PON, now closed to its bottom contact.y to ground at the armature andfront contact of group relay 17. rPhe test brush 33 of thev line finder,in passing over the test terminals 40, energizes in succession thecut-olf relays 12 of the lines of the calling group. When the terminals40, 4l., 42 of the calling line are reached, the energizalion of thecutoli' relay 12` thereof de'energizes the line relay 10, which, inallowing its armature to retract, opens the circuit of the group relay17. 'lhe retraction of the armature of group relay 17 opens the circuitof the secondaryv stepping magnet 34, thus stopping the finder brushes31, 32, 33, upon the terminals 41, 42, 40 of the calling line, thusextending the, calling line by way of conductors 43, 44 to the steppingrelays 53 of a first selector. The (leenergization of the relay 17, uponthe opera tion of the cutoii' relay 12, also denergizes relay 3S.

The energia-ation of relay 38, upon the attraction of the armature ofgroup relay 17 when the call was initiated, closed a circuit for a relay50 to open the connection of the battery to the brushes 32 during theectting of the finder on t'ne calling line, to prevent interference withexisting connections. This'circuit is as follows: free pole of battery,vrelay 50, conductor 51, 52, armature and front Contact 53 of relay 38,starter wire 22, including spring PON and its lower contact armature andfrontvcontact of group ;Th'e denergization of relay 3.8, upon the:finding of the line, vcauses the release of this relay' 50, which atits `armature and back contacts associates the stepping relay 53 of thefirst selector with conductors 43, 44. This stepping relay is adaptedtobe intermittently operated by the sender S at calling substation A. inthe well-knq9wn manner, to set the first selector in operative relationto the desired group of trunks. The trunk hunting operation thenfollows. lSince this part of the system is not claimed herein, it is notshown in detail. that during conversation, relay. 50 is locked up in acircuit controlled by the lirstselec'- tor, and when this selector isreleased, upon the breaking down of the connection, a

ground is placed upon conductor 46 leading It is suiieient to statelback to the-finder. .The grounding of conductor 46 energizes the releasemagnet 45 to release the `finder over the following, circuit: magnet 45,finder off-normal contact PONE, conductor 49, lower armature and backcon'- tact offrelay 38, conductor 46, to ground.

The release magnet 45 then closes the circuit of 'relay H50. When thefinder reaches its normal position the release magnet 45becomesdenergized by the opening of spring PONZ, and denergizes relay50. Thus the connection to brushes 31, 32 is also opened during therestoration of the finder to prevent interference. lt will oe understoodthat while the calling line is shown as extended to a first selector,the invention is just as applicable to a-system'wherein the calling lineie extended to an operators position.

lll'lhat .is `claimed is: li v, v l. ln combination, groups of lines,lndere wherein said linee terminate in multiple contacte, a startingconductor adapted to preselect an idle Ender, a group switch aseociatedwith each inder and having a multiple contact for each grou and a brushadapted to cooperate therewith, a relay Jfor each group adapted normallyto maintain ground upon. its group contact, a line relay tor cach lineadapted to energize the correeponding group relay, and primary andsecondary magnets for each iinder, of av circuit' for said primarymagnet closed upon 'the energization of a group relay and leadingthrough an ofi-normal Contact4 of said finder, a control relay thereforenergized in parallel therewith, circuits for said relayi including afront contact thereof and grounded contacte of non-calling groups, acirc it for said secondary magnet controlled ata hack Contact of saidcontrol relay, and means Y for opening said circuit when the callingline `ie reached.

ln combination.,l groups of lines, linders wherein said lines terminatein multiple contacte, multiple test terminals for the lines in saidndere, a starting conductor adapted to presilect an idle finder, a groupswitch 'as,

sociated with each finder and having a. multiple contact for eachgrouprand a brush adapted to coperate therewith, a relay for eac-n groupadapted normally to maintain ground upon ite group contact, a line relayfor caen line adapted to energize the corresjionding group relay, andprimary and eecondaiy magnete for each finder, of a circuit for saidprimary magnet closed upon the energization of a group relay and leadingthrough.- an olf-normal contact of said linder, a control relay thereforenergized in parallel therewith, circuits for said relay including afront Contact thereof and grounded/contacts of non-calling groups, acircuit for said secondary magnet controlled at a back contact oi' saidcontrol relay and a frontcontact of said group relay, and a cutoii'relay for each line connected to the test terminal of said line in thefinder and i adapted to to be operated when the calling line is reachedto denergize the line relay to cause the group relay to open the second-.ary stepping circuit.

3. The combination with an automatic switch, primary and secondarymagnets therefor, a control relay, a circuit for energizing said primarymagnet and said relay simultaneously, a circuit for continuing theoperation of said magnet including an armature and front contact ofsaidrelay, and an operating circuit for saidsecondary magnet includingan armature and 'back contact- Ieiner e. DUNHAM.

an armature

